This invention relates to a method and system for fluid power generation. In particular, the invention relates to a method and system for fluid power generation by means of an oscillating fluid power generator.
In an age of fossil fuel depletion and high energy prices, wind power is a preferred choice for those wishing to power society in a sustainable manner and in a manner which does not cause harm to our environment. Unfortunately, wind power itself is not free from controversy as some react with alarm to the prospect of unsightly large windmills dotting the landscape. Furthermore, turbines can injure or kill birds and bats and interfere with radio frequency (RF) transmissions.
The background art is characterized by U.S. Pat. Nos. 252,947; 1,274,545; 1,633,460; 3,442,493; 3,647,315; 3,743,848; 3,785,213; 3,995,972; 4,024,409; 4,251,040; 4,298,313; 4,346,305; 4,387,318; 4,486,145; 4,496,848; 4,525,122; 4,536,674; 4,582,013; 4,684,817; 5,009,571; 5,193,978; 5,324,169; 5,844,323; 6,153,944; 6,273,680; 6,320,273; 6,652,232; 6,700,218; 6,731,018; 6,734,576; 6,853,096; and 6,926,491; and U.S. patent application Ser. Nos. 2002/0079705, 2003/0123983; and 2005/0141994; the disclosures of which documents are incorporated by reference as if fully set forth herein. The background art is also characterized by the disclosures of the following patent documents: GB 2073327; EP 683316 and EP 490830.
State-of-the-art wind turbines (as well as older wind turbines) have a number of major technical drawbacks that make them expensive to manufacture as well as maintain: (1) they require designs that must overcome great forces at the blade root, including bending in two axes and large torsional loads; they must also resist very large centrifugal forces as well as loading fluctuations caused by wind shadowing from the tower or local ground effect; (2) the towers that support wind turbines must resist high overturning moments at their base due to the very high forces concentrated at the center of the rotor; because of the large rotor blade size in larger systems, towers cannot be guyed; this requires the towers to be constructed of very strong and expensive materials, contributing substantially to the overall system cost; (3) the high-rotation tip speeds of smaller and older large-scale turbines presents a lethal threat to birds and bats; much of the public objection to wind turbines is based on the perception that they contribute to a high death rate for these animals; in addition, many wind turbines are perceived to be noisy; (4) high-lift-capable service equipment is often required for maintenance of the motor/generators that are necessarily located at the top of the wind-turbine towers in horizontal-axis wind turbine systems; (5) in order to withstand very high winds, turbine blades in modern conventional horizontal-axis wind turbine systems must be allowed to feather by rotating the blades approximately 90 degrees along their longitudinal axes, which requires complex and expensive gearing; in Darrieus-type vertical-axis wind turbine systems, the blades cannot be feathered and powerful mechanical brakes or other speed control devices must be employed, increasing the expense of manufacture; (6) Darrieus-type systems are not self-starting and require motors to get the blades rotating at a functional speed; and (7) turbines must be fairly widely spaced to minimize side-by-side and tandem interference with neighboring installations. In conclusion, relatively expensive materials and sophisticated, costly manufacturing techniques are required for wind turbine components, including blades, gearboxes, bearings, and towers. In addition, many systems, especially older, utility-scale systems, require costly maintenance.